Update spring-statemachine to 4.0.0 (#5707)

This should make skipper to start and run. 
Simple ticktock stream shouldwork ok.

Author: jvalkeal

spring-cloud-skipper/pom.xml

@@ -24,7 +24,7 @@
 		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 		<java.version>17</java.version>
 
-		<spring-statemachine.version>2.5.1</spring-statemachine.version>
+		<spring-statemachine.version>4.0.0</spring-statemachine.version>
 		<spring-cloud-deployer.version>2.9.3-SNAPSHOT</spring-cloud-deployer.version>
 
 		<zeroturnaround.version>1.15</zeroturnaround.version>

spring-cloud-skipper/spring-cloud-skipper-server-core/src/main/java/org/springframework/cloud/skipper/server/statemachine/StateMachineConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2019 the original author or authors.
+ * Copyright 2017-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,7 +30,6 @@
 import org.springframework.cloud.skipper.server.statemachine.SkipperStateMachineService.SkipperVariables;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.core.task.TaskExecutor;
 import org.springframework.statemachine.StateMachinePersist;
 import org.springframework.statemachine.config.EnableStateMachineFactory;
 import org.springframework.statemachine.config.StateMachineConfigurerAdapter;
@@ -76,9 +75,6 @@ private static long adjustTimerPeriod(HealthCheckProperties healthCheckPropertie
 	@Configuration
 	public static class SkipperStateMachineFactoryConfig extends StateMachineConfigurerAdapter<SkipperStates, SkipperEvents> {
 
-		@Autowired
-		private TaskExecutor skipperStateMachineTaskExecutor;
-
 		@Autowired
 		private ReleaseService releaseService;
 
@@ -101,7 +97,6 @@ public static class SkipperStateMachineFactoryConfig extends StateMachineConfigu
 		public void configure(StateMachineConfigurationConfigurer<SkipperStates, SkipperEvents> config) throws Exception {
 			config
 				.withConfiguration()
-					.taskExecutor(skipperStateMachineTaskExecutor)
 					// this is to simply add logging for state enters
 					.listener(new StateMachineListenerAdapter<SkipperStates, SkipperEvents>() {
 						@Override

spring-cloud-skipper/spring-cloud-skipper-server-core/src/main/java/org/springframework/cloud/skipper/server/statemachine/StateMachinePersistConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 the original author or authors.
+ * Copyright 2017-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@
 package org.springframework.cloud.skipper.server.statemachine;
 
 import java.util.Map;
+import java.util.function.Function;
 import java.util.stream.Collectors;
 
 import org.springframework.cloud.skipper.server.statemachine.SkipperStateMachineService.SkipperEvents;
@@ -29,7 +30,6 @@
 import org.springframework.statemachine.data.jpa.JpaStateMachineRepository;
 import org.springframework.statemachine.kryo.KryoStateMachineSerialisationService;
 import org.springframework.statemachine.persist.StateMachineRuntimePersister;
-import org.springframework.statemachine.support.Function;
 import org.springframework.util.ObjectUtils;
 
 /**